1. Field of the Invention
The present invention relates to a reel detecting mechanism for optically detecting the reel rotation in a video cassette deck.
2. Description of Prior Art
In video cassette decks, an optical leading end and entraining end detecting mechanism is used so as to detect the leading end and the entraining end of the magnetic tape within a cassette set within the deck. The rotation of the reel is often detected optically by the common use of the leading and entraining end detecting mechanism and partial components. A reel detecting mechanism for commonly using the leading and entraining end detecting mechanism such as magnetic tape and its partial components are described in, for example, Japanese Patent Application Laid-Open No. 8-17095 and Japanese Application Laid-Open No. 129794.
FIG. 2 is a schematic plan view of a reel rotation and detection mechanism described in Japanese Patent Application Laid-Open No. 8-17095. Magnetic head cylinder, reels 10a, 10b and so on which are the major components of the video cassette deck are mounted on a deck chassis 20.
The reel rotation and detection mechanism has a light emitting element 41 provided above the deck chassis 20. The light emitting element 41 emits the light in two directions from the common use relationship between the leading end and entraining end detecting mechanism of the magnetic tape to be described later. One light to be emitted from the light emitting element 41 is divided into two directions by the light guiding member 52 for reel rotation and detection use and is guided to the light receiving elements 51a and 51b by way of the light transmitting portions 54a and 54b provided in the reel 10a and 10b. The light transmitting portions 54a and 54b are formed in the cylindrical portion provided in the lower portions of the reels 10a and 10b, while the light receiving elements 51a and 51b are provided, above the deck chassis 20, on the inner side of the cylindrical portion.
The leading and entraining end detecting mechanism of the magnetic tape 1 divides the other light transmitted from the light emitting element 41 by a light guiding member 43 for the leading and entraining end detection use, so as to guide the light in the light receiving elements 42a and 42b by way of within the cassette 2. The light receiving elements 42a and 42b, together with the light emitting element 41 and the light receiving elements 51a and 51b for rotation detecting use, are provided above the deck chassis 20.
In this manner, the reel rotation and detection mechanism described in Japanese Patent Application Laid-Open No. 8-17095 commonly uses the light emitting element 41 between the leading and entraining end detecting mechanism of the magnetic tape 1.
FIG. 3 is a schematic elevation view of the reel rotation and detection mechanism described in Japanese Patent Application Laid-Open No. 8-129794. The reel rotation and detection mechanism is different in the common use of the light emitting element 41 and the light guiding member 52 between the the leading and entraining end detecting mechanism of the magnetic tape. The light emitting element 41 is engaged on the main substrate 30 provided under the deck chassis 20. The light receiving element 51 for reel rotation and detection use is provided on the chassis 20 through a housing 31, because it is not engaged directly on the main substrate 30 from the relation of the position on the inner side of the cylindrical portion 12 provided in the lower portion of the reel 10 although it is provided on the main substrate 30.
The reel rotation and detection mechanism is economical in that one portion of the components is commonly used between the leading end and entraining end detecting mechanism of the magnetic tape. Since the light receiving element 51 and further, the light receiving elements 42a and 42b for the leading end and the entraining end detecting use are positioned above the deck chassis 20 and are separated from the main substrate 30, whereby the wiring configuration and so on become complicated. Thus, a type is developed, wherein these light receiving elements, together with the light emitting element are positioned under the deck chassis 20, and are engaged directly on the main substrate 30.